The Lifetime show needs to take seriously its premise of a mom who plays guitar.

Lifetime Television, no longer officially the Network for Women (but unofficially, yes, still), tonight presents its first situation comedy in a decade, "Rita Rocks." Its last attempts, which were also its first, were the very good "Maggie," with Ann Cusack as a woman contemplating adultery, and "Oh Baby," starring Cynthia Stevenson as an artificially inseminated single mom. They kept the network's interest for one and two seasons, respectively. I remember them as smart and different in tone from anything else on at the time.

Like those series, "Rita Rocks," which runs new episodes every night this week before taking up a regular Tuesday slot next week, is built around an unconventionally attractive, mature female lead experiencing a self-defining moment of change. (By "unconventionally attractive," I mean she's pretty in a normal, not Hollywood, way, and by "mature," I mean she's over 35.) Nicole Sullivan, whose many credits include long runs on "MadTV" and "The King of Queens," plays the eponymous Rita, an Anywhereville wife and mother of two who takes care of everyone but herself. (I see this type on "What Not to Wear" all the time.) "The blond in the dented Datsun" is how she identifies herself over the phone to the mother of one of her younger daughter's friends.

I like the premise, or at least what I take to be the premise -- suburban mom in a midlife crisis gets guitar and goes back to the garage. Well, actually, she goes back to the garage to get the guitar, where she is extracted from a comical situation (hanging from the rafters) by sparky, nosy mail carrier Patty (Tisha Campbell-Martin).

On the basis of her subscriptions to Women's Day and the Cupcake of the Month Club, Patty pegs Rita as dishwater dull. Rita sees her point but protests, "On the inside, I'm a firecracker." Patty knows what she means: Under her "itchy blue shorts lies a fierce diva -- that's right, I play a mean organ."

And so they arrange a play date. "Come on," says Patty, turning on her mean organ. "Let's jam!"

"I miss jammin'," says Rita, who had once been in a Bangles cover band.

A few chords bring over a sad-sack unemployed neighbor (Ian Gomez, bass).

Back in the house are her husband, Jay (Richard Ruccolo), who does not take her renewed ambitions quite seriously at first; younger daughter Shannon (Kelly Gould), from the Angela Cartwright School of Precocious Little Girls; boundary-testing older daughter Hallie (Natalie Dreyfuss); and Hallie's permanent-fixture boyfriend, Kip (Raviv Ullman), who winds up playing "the drums" -- just an arrangement of household odds and ends -- in Rita's sort-of band.

With one thing and another, it looks like no music will be ever made, but in the end they improvise a rather sweet version of Otis Redding's "Try a Little Tenderness" -- not the easiest song to grab from the air. I'd think it would take only a couple of weeks before they'd have enough stuff together to start booking weddings and bar mitzvahs.

Unfortunately, based on the two episodes I've seen (Nos. 1 and 3, which is about Hallie wanting a tattoo and Patty dating a UPS guy) and synopses of five others, it seems music will be the least of the show's concerns. It'll be too bad if that's true, because it's the one element that promises something new. Sullivan is a sprightly performer with a charming singing voice, and when Campbell-Martin falls into harmony with her, it's a lovely moment.

But without exploring the specificity of the band experience, she might be doing anything in that garage -- throwing pots, teaching yoga or working on a motorcycle, whatever. The rest of it's just a somewhat underachieving three-camera family sitcom, with a door there, stairs here and a kitchen over there, filled with good actors, mechanically efficient jokes and few surprises.

Created by Stan Zimmerman and James Berg, who have written for shows from "The Golden Girls" to "Gilmore Girls," "Rita Rocks" is not awful by any means, just awfully familiar. But it would be nice to see all this talent, money and time spent on something that pushes a little further, and that takes its own premise seriously.